Magnetic tape cartridge

ABSTRACT

A magnetic tape cartridge includes a cartridge case, a single tape reel, and a tape leader pin. The cartridge case has a tape leader opening in the side wall thereof. The tape reel with magnetic tape wound thereon is rotatably housed within said cartridge case. The tape leader pin is firmly attached to the leading end of said magnetic tape and is detachably held near the tape leader opening by a spring member. The surface hardness of the sliding surface of the spring member with respect to said tape leader pin is made higher than that of the tape leader pin to prevent an increase in the sliding resistance between the sliding surface of the tape leader pin and the sliding surface of a leader-pin holding spring.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic tape cartridge, in which asingle tape reel with magnetic tape wound thereon is rotatably housedwithin a cartridge case, and in which a tape leader pin for pulling themagnetic tape out of the cartridge case is firmly attached to theleading end of the magnetic tape.

2. Description of the Related Art

In magnetic tape cartridges, which are being used as storage media thatare employed in external storage units for computers, etc., there isknown a type where a single tape reel with magnetic tape wound thereonis rotatably housed within a cartridge case. This magnetic tape isemployed to archive data for computers, etc. Since important informationhas been stored, the magnetic cartridge is constructed so that problems,such as tape jamming, etc., do not occur and that the magnetic tape isnot pulled out of the cartridge case inadvertently.

The magnetic tape has an elongate tape leader pin firmly attached to theleading end thereof. When this magnetic tape cartridge is loaded into arecording-reproducing unit, a leader-pin catching member on the side ofthe recording-reproducing unit engages the tape leader pin and pulls outthe magnetic tape from the cartridge case. On the other hand, when themagnetic tape cartridge is unloaded from the recording-reproducing unit,the magnetic tape is rewound on the tape reel and the tape leader pin isreturned into the cartridge case by the leader-pin catching member. Thecartridge case is formed by fastening upper and lower cases of syntheticresin together with a plurality of small screws. Near a tape leaderopening formed in the cartridge case, the tape leader pin is detachablyheld at the upper and lower ends thereof by a spring member.

The spring member for detachably holding the tape leader pin,incidentally, repeats sliding action each time the magnetic tapecartridge is loaded into or unloaded from the recording-reproducingunit. Because of this, the sliding surfaces of the tape leader pin andthe spring member are worn away and the sliding resistance therebetweenincreases. As a result, the pulling-in-and-out of the tape leader pinthrough the tape leader opening cannot be smoothly performed. In theworst case, the pulling-in-and-out of the tape leader pin cannot beperformed at all.

In addition, in the case that the spring member is formed from a platespring, it is punched out from a plate, and consequently, burrs areliable to occur at the edge. If there are burrs on the sliding surfaceof the elastic arm portion of the spring member (plate spring) thatcontacts the tape leader pin, when the sliding surface of the elasticarm portion abuts the tape leader pin to hold the tape leader pin, theburrs cause scoring of the tape leader pin surface every time slidingaction is performed between the elastic arm portion and the tape leaderpin (i.e., when the magnetic tape cartridge is loaded into or unloadedfrom the recording-reproducing unit). Because of this, the slidingresistance between the elastic arm portion and the tape leader pin isincreased. Consequently, the pulling-in-and-out of the tape leader pinthrough the tape leader opening cannot be smoothly performed. In theworst case, there is a fear that the pulling-in-and-out of the tapeleader pin cannot be performed at all.

SUMMARY OF THE INVENTION

The present invention has been made in view of the circumstancesmentioned above. Accordingly, it is the primary object of the presentinvention to provide a magnetic tape cartridge that is capable ofpreventing an increase in the sliding resistance between the slidingsurface of a tape leader pin and the sliding surface of a spring memberfor holding the tape leader pin.

To achieve this end, there is provided a first magnetic tape cartridgecomprising:

a cartridge case with a tape leader opening in a side wall;

a single tape reel having magnetic tape wound thereon and rotatablyhoused within the cartridge case; and

a tape leader pin, firmly attached to a leading end of the magnetictape, and detachably held near the tape leader opening by a springmember;

wherein a surface hardness of a sliding surface of the spring memberwith respect to the tape leader pin is higher than that of the tapeleader pin.

It is preferable that the difference in hardness between the slidingsurfaces of the tape leader pin and the spring member is made greater,as wear on the sliding surface of the spring member is reduced thereby.For example, the tape leader pin is formed from relatively soft metalmaterial such as aluminum, or thermoplastic resin such as polycarbonateresin. The sliding surface of the spring member with respect to the tapeleader pin is electro-plated with chromium or nickel so that it has asurface hardness H_(v) of 500 to 700. In this manner, the presentinvention is capable of preventing an increase in the sliding resistancebetween the sliding surfaces of the tape leader pin and the springmember.

According to the first magnetic tape cartridge of the present invention,the surface hardness of the sliding surface of the spring member withrespect to the tape leader pin is higher than that of the tape leaderpin. Because of this, the surface of the spring member is not worn away,and only the tape leader pin is worn away. Since the tape leader pin canbe easily exchanged for a new one, the state of the sliding surfaces ofthe spring member and the tape leader pin can always be ideallymaintained.

In a second magnetic tape cartridge of the present invention, at leasteither a sliding surface of the spring member or a sliding surface ofthe tape leader pin is subjected to a surface roughening process.

The surface roughening process can be performed by barreling. With thesurface roughening process, the sliding surface has fine unevenness thatis called a grain or dimple. It is preferable that the surface roughnessbe in a range of 0.5 to 3.0 μm in terms of 10-point mean roughness.

According to the second magnetic tape cartridge of the presentinvention, at least either a sliding surface of the spring member or asliding surface of the tape leader pin is roughened. Because the slidingresistance between the two sliding surface is reduced, wear on thesliding surface of the spring member and/or the sliding surface of thetape leader pin is prevented. Thus, the state of the sliding surfaces ofthe spring member and the tape leader pin can be ideally maintained.

In a third magnetic tape cartridge of the present invention, the springmember consists of a plate spring, and at least a sliding surface of theplate spring with respect to the tape leader pin is subjected to asurface striking process.

According to the third magnetic tape cartridge of the present invention,the sliding surface of the plate spring with respect to the tape leaderpin is subjected to the surface striking process. Since there are noburrs due to punching, there is no fear that the surface of the tapeleader pin will be scored by burrs due to punching. Thus, third magnetictape cartridge of the present invention is capable of preventing anincrease in the sliding resistance between the sliding surface of thetape leader pin and the sliding surface of the plate spring.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in further detail with referenceto the accompanying drawings wherein:

FIG. 1 is an exploded perspective view showing a magnetic tape cartridgeconstructed according to the present invention;

FIG. 2 is a front view of the vicinity of the tape leader opening shownin FIG. 1, a slide door being opened to show the tape leader opening;

FIG. 3 is a plan view of the vicinity of the tape leader opening shownin FIG. 1, with the upper case removed to show how a tape leader pin isheld by a leader-pin holding spring; and

FIG. 4 is a perspective view of the leader-pin holding spring shown inFIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will hereinafter be described indetail with reference to the drawings. Note that a fore-and-aftdirection in this embodiment corresponds to a direction in which amagnetic tape cartridge is loaded into a magnetic recording-reproducingunit (i.e., the direction diagonal to the upper right of FIG. 1 or theright direction in FIG. 3).

In FIG. 1, the magnetic tape cartridge 1 has a cartridge case 4, whichis formed by fastening an upper case 2 and a lower case 3 together withfour small screws 30. A tape leader pin 5 is firmly attached to theleading end of magnetic tape 6, and a single tape reel 7 with themagnetic tape 6 wound thereon is rotatably housed within the cartridgecase 4. The upper and lower cases 2, 3 are approximately rectangular inshape, and are provided with top and bottom walls 2 b, 3 b, and upperand lower side walls 2 a, 3 a along the perimeters of the top and bottomwalls 2 b, 3 b. The upper and lower cases 2, 3 are further provided witharcuate inside walls 3 c (not shown for the upper case 2) extendingalong the outer periphery of the tape reel 7. The four boss portions 3 dof the lower case 3, each disposed between the side wall 3 b and theinside wall 3 c, are aligned vertically with the four boss portions 2 dof the upper case 2, and the upper and lower cases 2, 3 are fastenedtogether by the small screws 30 inserted through the bottom surface ofthe lower case 3.

The lower case 3 has a center aperture 3 e at the central portionthereof so that the tape reel 7 is rotated by the driving shaft of acartridge drive unit (not shown). The cartridge case 4 has a slidablewrite protect member 13 at the rear end portion thereof to inhibitwriting onto the magnetic tape. The central portion of the tape reel 7is provided with a locking mechanism 15 for restricting rotation of thetape reel 7 when it is not being used.

Although not shown, the tape reel 7 has a reel plate mounted on thecentral portion of the bottom surface thereof, the reel plate being usedto attract and hold the magnetic rotation drive means of the cartridgedrive unit. The radially outer portion of the bottom wall of the tapereel 7 is provided with a reel gear (not shown) which meshes with thedriving gear of the rotation drive means. Note that if the reel gear andthe driving gear mesh with each other, the locking mechanism 15 isunlocked so that the tape reel 7 is free to rotate.

The side walls 2 b, 3 b of the upper and lower cases 2, 3 are providedwith a tape leader opening 10 through which the tape leader pin 5 of themagnetic tape 6 is pulled in and out of the cartridge case 4. The tapeleader opening 10 is opened or closed by a slide door 11 urged in aclosing direction by a spring (not shown). Near the tape leader opening10, there is formed a grooved door rail 12 (see FIG. 3) along which theslide door 11 slides.

In the magnetic tape cartridge 1, as shown in FIG. 3, the tape leaderpin 5 is locked and held in upper and lower leader-pin housing recesses20, 20 formed near the tape leader opening 10, with the magnetic tape 6completely wound on the tape reel 7 during non-use of the cartridge 1.The upper and lower leader-pin housing recesses 20, 20 are continuous toupper and lower insertion-guide portions 21, 21 (guide surfaces) formedinto a lead-in structure toward the tape leader opening 10. That is, theupper and lower insertion-guide portions 21, 21 are constructed so thatthe upper and lower end portions of the tape leader pin 5 can be guidedto the interior upper and lower leader-pin housing recesses 20, 20.

The tape leader pin 5 is pulled out of the cartridge case 4 through thetape leader opening 10 by a leader-pin catching member (not shown)provided in the drive mechanism of a recording-reproducing unit, inorder to introduce the magnetic tape 6 into a tape traveling path formedwithin the recording-reproducing unit.

The tape leader pin 5 consists of a pin main body of metal and a clampmember 5 e of synthetic resin. As shown in FIG. 2, the pin main body isconstructed of a core shaft portion 5 a (indicated by a dashed line) towhich the leading end of the magnetic tape 6 is clamped; thin flangeportions 5 b, 5 b formed at the upper and lower ends of the core shaftportion 5 a; engagement shaft portions 5 c, 5 c formed outside the thinflange portions 5 b, 5 b as portions that are engaged by the leader-pincatching member; and thick flange portions 5 d, 5 d formed outside theengagement shaft portions 5 c, 5 c. The clamp member 5 e has a C-shapedcross section (having a slit) and is fitted elastically onto the outerperiphery of the core shaft portion 5 a. As a result, the leading end ofthe magnetic tape 6 is clamped (or firmly attached) between the coreshaft portion 5 a and the clamp member 5 e.

The upper and lower cases 2, 3 are provided with a leader-pin holdingspring 9, which consists of a plate spring such as that shown in FIG. 4,to detachably hold the upper and lower end portions of the tape leaderpin 5 in the upper and lower leader-pin housing recesses 20, 20. Theupper and lower portions of the leader-pin holding spring 9 are formedintegrally. The leader-pin holding spring has a mounting portion 9 a inthe form of a generally rectangular plate. With the upper case 2 and thelower case 3 stacked on each other, the mounting portion 9 a is engagedand held by upper and lower spring installing portions 23 provided nearthe case side walls (front walls) 2 b, 3 b, as shown in FIG. 3. Althoughnot shown, the upper case 2 is symmetrical in shape with the lower case3. The leader-pin holding spring 9 also has a pair of elastic armportions 9 b, 9 b extending obliquely from the upper and lower endportions of the mounting portion 9 a toward the tape leader pin 5. Theelastic arm portions 9 b, 9 b have leader-pin holding portions 9 c, 9 cat their outer ends, respectively. The leader-pin holding portions 9 c,9 c elastically abut the outer peripheries of the upper and lower flangeportions 5 d, 5 d of the tape leader pin 5. As shown in FIG. 3, eachleader-pin holding portion 9 c is bent so that it projects toward thetape leader pin 5. The bent portion of the leader-pin holding portion 9c consists of an outer inclined surface and an inner inclined surface.If the tape leader pin 5 is inserted through the tape leader opening 10,the upper and lower flange portions 5 d, 5 d of the tape leader pin 5are brought into contact with the outer inclined surfaces of the bentportions of the upper and lower leader-pin holding portions 9 c, and theupper and lower elastic arm portions 9 b, 9 b are elastically deformed.As a result, the upper and lower flange portions 5 d, 5 d of the tapeleader pin 5 are held within the upper and lower leader-pin housingrecesses 20, 20 by the inner inclined surfaces of the bent portions ofthe upper and lower lead-pin holding portions 9 c of the leader-pinholding spring 9. In addition, the top and bottom edges of the mountingportion 9 a are provided with engagement recesses 9 d, 9 d,respectively.

The lower spring installing portion 23 of the lower case 3, for holdingthe leader-pin holding spring 9, is equipped with two ribs 23 a and 23 aformed on the interior surface of the side or front wall 3 b of thelower case 3; a first protrusion 23 b erected in the top surface of thelower case 3; a second protrusion 23 c formed between the two ribs 23 aand 23 a. Similarly, the upper spring installing portion (not shown) ofthe upper case 2 is equipped with two ribs (not shown), a firstprotrusion (not shown), and a second protrusion (not shown). If theupper and lower portions of the mounting portion 9 a of the leader-pinholding spring 9 are inserted between the upper ribs and the upper firstprotrusion and between the lower ribs 23 a and the lower firstprotrusion 23 b, the upper and low second protrusions 23 c are fittedinto the upper and lower engagement recesses 9 d, 9 d of the mountingportion 9 a of the leader-pin holding spring 9. In this manner, theleader-pin holding spring 9 is held by the upper and lower springinstalling portions 23. Furthermore, the spring installing portions 23are provided with tilt regulating portions 23 d, which are used to holdthe edge, opposite to the elastic arm portions 9 b, of the mountingportion 9 a of the leader-pin holding spring 9 in an upright state.

In the first embodiment of the present invention described above, theleader-pin holding spring 9 with elastic arm portions 9 b, 9 b is formedfrom Steel Use Stainless (SUS) material (e.g., SUS304), and the surfacehardness H_(v) of the leader-pin holding portions 9 c, 9 c is increasedto about 500 to 700 by chromium plating or nickel plating. On the otherhand, the pin main body of the tape leader pin 5, equipped with theflange portions 5 d, 5 d, is formed from aluminum, and the surfacehardness H_(v) is about 50 to 200. With this hardness difference betweenthe tape leader pin 5 and the leader-pin holding spring 9, wear on thesliding surfaces of the leader-pin holding spring 9, which contact withthe flange portions 5 d, 5 d of the tape leader pin 5, is prevented.

Thus, in the case where the surface hardness of the outer end portionsof the elastic arm portions 9 b, 9 b of the leader-pin holding spring 9is higher by far than that of the flange portions 5 d, 5 d of the tapeleader pin 5, the outer end portions of the elastic arm portions 9 b, 9b of the leader-pin holding spring 9 are not worn away and only theouter peripheral surfaces of the flange portions of the tape leader pin5 are worn away, when the magnetic tape cartridge 1 repeats loading andunloading operations for a long period of time. Therefore, if aworn-away tape leader pin is exchanged for a new one, the slidingresistance between the sliding surfaces of the tape leader pin 5 and theleader-pin holding spring 9 can be prevented from being increased togreater than a predetermined amount.

In a second embodiment of the present invention, the sliding surfaces ofthe leader-pin holding portions 9 c, 9 c of a leading-pin holding spring9 that contact with the tape leader pin 5 are roughened, for example, bybarreling. It is preferable that the surface roughness of the slidingsurfaces be in a range of 0.5 to 3.0 μm in terms of 10-point meanroughness. Note that roughening of the sliding surface may be performednot on the leader-pin holding spring 9 but on the tape leader pin 5, ormay be performed on both the leader-pin holding spring 9 and the tapeleader pin 5.

Thus, the sliding resistance between the sliding surfaces can be reducedby roughening at least either the sliding surface of the leader-pinholding spring 9 or the sliding surface of the tape leader pin 5. Sincewear on the leader-pin holding spring 9 and/or the tape leader pin 5 isprevented, the state of the sliding surfaces of the leader-pin holdingspring 9 and the tape leader pin 5 can be ideally maintained.

Furthermore, in a third embodiment of the present invention, burrs dueto punching are removed by performing a surface striking process on atleast the sliding surfaces of the elastic arm portions 9 b, 9 b of theleader-pin holding spring 9.

Thus, in the third embodiment of the present invention, a surfacestriking process is performed on at least the sliding surfaces of theelastic arm portions 9 b, 9 b of the leader-pin holding spring 9, sothere is no fear that the surface of the tape leader pin 5 will bescored by burrs due to punching. Thus, the third embodiment is capableof preventing an increase in the sliding resistance between the slidingsurfaces of the leader-pin holding spring 9 and the tape leader pin 5.

While the present invention has been described with reference to thepreferred embodiments thereof, the invention is not to be limited to thedetails given herein, but may be modified within the scope of theinvention hereinafter claimed.

1-7. (canceled)
 8. A magnetic tape cartridge comprising: a cartridgecase with a tape leader opening in a side wall; a single tape reelhaving magnetic tape wound thereon rotatably housed within saidcartridge case; and a tape leader pin, firmly attached to a leading endof said magnetic tape, and detachably held near said tape leader openingby a spring member; wherein at least either a sliding surface of saidspring member or a sliding surface of said tape leader pin is subjectedto a surface roughening process.
 9. The magnetic tape cartridge as setforth in claim 8, wherein the sliding surface subjected to said surfaceroughening process has a surface roughness of 0.5 to 3.0 μm in terms of10-point mean roughness.
 10. A magnetic tape cartridge comprising: acartridge case with a tape leader opening in a side wall; a single tapereel having magnetic tape sound thereon rotatably housed within saidcartridge case; and a tape leader pin, firmly attached to a leading endof said magnetic tape, and detachably held near said tape leader openingby a spring member comprising a plate spring; wherein at least a slidingsurface of said plate spring with respect to said tape leader pin issubjected to a surface striking process.